| The wastewater treatment technology with aerobic granule sludge is a new technique developed in recent years.It can be applied to remove organic compounds, COD,ammonia,refractory toxic organic compounds,parathion as well as the wastewater with heavy metal and so on.Compared with conventional activated sludge system,the aerobic granule has strong and compact microbial structure,improved stability and higher biomass retention,the process of effluent separating is simple,the structure of the reactor is compact,which can leave out the second settling and refluence device,the occupied area is small;the system can withstand the unfavorable hydraulic effect and toxic substances;compared with anaerobic granules,the aerobic granules are more stable when used to treat the organic wastewater of low concentration,and the start-up period is much shorter than that of the anaerobic granules.Floccular activated sludge was used as seeding sludge.On the condition of organic loading rate at 11.2kgCOD/(m3·d),operation cycle under 3 hours and superficial air velocity at 2.22cm·s-1,aerobic granular sludge was successful cultivated in sequencing batch reactor(SBR) fed with synthetic wastewater.The experiment with the methods of high hydraulic shear stress and gradually reducing sludge settlement time quickly cultivate aerobic granular sludge,which outward appearance is light yellow.Aerobic granular sludge have a clear outer shape,good outline,compact structure and high settling ability.Its particle diameter concentrate in 5-6mm,sludge volume index SVI is about 25m1/g,MLSS is high to 5960mg/L and the average of sedimentation rate is about 41.2m/h.Finally,the experiment show that high hydraulic shear stress is good for the formation of aerobic granular sludge.The aerobic granular sludge in the experiment have good removal ability to nitrogen and phosphorous.With the influent of ahout 1000mg/LCOD,80mg/L NH3-N,18 mg/L TP and operation cycle under 3 hour,the COD,NH3-N and TP removal efficiencies of the aerobic granular sludge were about 93.2%,85.7%and 93.4%.When we do not change the condition of the influent,superficial air velocity and so on,only to change the operation cycle under 6 hour,the COD removal efficiency remains a conant in 93.2%.Simultaneity the NH3-N and TP removal efficiencies were change to 91.2%,95.8%.It tell us that the nitrogen and phosphorous removal efficiencies are not to maximize when the operation cycle is 3 hours.Compare with the experiments,we draw a conclusion that the optimize operation cycle is 6 hours for removing to nitrogen and phosphorous.
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